Our new paper submitted to the SMI 2020 conference,
which shows how a classic implicit surface representation, the I-patch,
can be used for non-trivial modeling tasks,
including setback vertex blends and polyhedral design.

An Emacs implementation of the
Tajik YQUKEN keyboard layout (a modification of the cyrillic JCUKEN layout).
There is also a version for IBus-m17n,
put it in your ~/.m17n.d/ directory. You may also need to un-blacklist it
in /usr/share/ibus-m17n/default.xml, by adding the following snippet at the end:

A memo on the VT100 control sequences
for my students, with which you can (i) clear the screen, (ii) move the cursor,
(iii) change the formatting/colors.
X11-specific window-controlling sequences are also touched upon.
(In Hungarian.)

A (very) short
paper
on the multi-sided generalization of the C0 Coons patch.
It draws on the same idea as the
CR patch,
but does not need normal information at the boundaries.
A simple, lightweight patch when C0 continuity with adjacent patches is sufficient.
See also my sample implementation.

A "dual"
Catchup board
printable on A4 paper (also in
PDF).
The size is just right to play with Go stones (triangle edges are 1" long),
but you will need smaller markers for the scoring track.
The game is played by two players with black and white Go stones.
The rules are simple:

First white places one stone on an intersection.

Then the two players alternately put 1, 2 or 3 stones on any empty intersections,
until the board is filled.

The winner is the player whose largest connected group has more stones;
or if it is a tie, then the second largest, and so on.

3 stones can only be played in a turn, if 2 conditions are met:
(i) the opponent moved forward on the scoring track in his/her last turn, and
(ii) we are not ahead of the opponent on the scoring track.

There are dice of various number of sides. But is there a 3-sided die? The answer is YES!
My original idea was that it should have 3 faces, and should be symmetrical. The
intersection of three spheres is like that.
Place the center of the spheres on the vertices of an equilateral triangle, and
make their radii somewhat larger than the side of the triangle (how much larger depends on
how "fat" you want the die to be).

Dara is a Nigerian board game similar to Nine Men's Morris (but much more complex).
Variations of it are played throughout West Africa. I have summarized
the rules, and created a simple
A4 PostScript board (also in
PDF). It is the perfect size to play with checkers pieces.

A simple EPS board for the Marrakech board game.
Each square is about 2.5 cm wide, so the carpets should be 2.5cm x 5cm, you can make 18 of them
from a standard 15cm square origami paper.
Also, here are the rules summarized in Hungarian.

See two photos of my travel Marrakech set:
the box and
while playing.
(Money is represented by black & white discs from a paper Go set; Assam is a Shogi pawn.)

If you take 4 of the right angle tetrahedra, and one regular tetrahedron,
you can also build a cube! The smaller sides of the papers should have
a ratio of 1:sqrt(3), so if you fold the right angle tetrahedra from a paper
of size (1,2), the regular tetrahedron should be folded from a paper of size
(sqrt(3),sqrt(6)).

There is an alternative version
of the right angle tetrahedron, foldable from a square paper. For the above
construction to work, the smaller side of the regular tetrahedron should be
3-sqrt(3).

A board for playing XiguaQi.
This is a simple two-player game where players move their pieces
along the lines to adjacent intersections.
Initially the 6-6 pieces are on the lower (upper) half of the board,
with the points of the central circle left empty.
When a piece or a group of pieces has nowhere to go, it is removed from the board.
The player who has less than 3 pieces loses.

My first (unit) origami design.
There are many ways to make cubes without creases on the faces,
there is e.g. John Montroll's from 1 square paper, or Miyuki Kawamura's from 6.
This is one using 3 squares - it is so simple, that someone else must have
done it before.

Another 2-unit cube
is folded from half-squares. It is somewhat small (the edges are 1/6
of the square's), but its surface area is 1/6 of that of the total used paper,
which is comparable to the other ones (3-unit: 2/9, 2-unit: 3/16).

Finally, I have found a box - an open cube -
also so simple that it must be already known.

As an exercise, I've tried to write up a 30-page introduction to
Persian grammar (in Hungarian), covering (almost) all the basic
constructions, along with some worked out example texts. The goal was to
create a document that can be read and understood with no previous
knowledge of the language.

A memo on how I found out
the continuous representation of a discrete curve
I used to doodle when I was a kid (in Hungarian).
[Note that, while similar, this is not an astroid:
drawing an astroid requires the "falling" line segment to be of constant length.]

I have recently bought the 2nd edition of "Arabic Today" (by John Mace),
which is a unique Arabic textbook, as it first teaches the colloquial language,
then moves on to the written language (normally it is the other way around).
I have found this approach very nice,
as the colloquial language does not impose such a burden on the learner,
and the transition is also quite easy, using the short pronunciation as a base.
The spoken language the book teaches is a kind of common educated language
that is not specific to any one region, and can be used anywhere in the Arab world.

The book does have its faults - there are no translation exercises, and the audio is worthless
(apart form the first three lessons, only some exercises have recordings).
Also, it focuses on business/media vocabulary a bit too much for my taste.
Still, it is the best textbook I know of.

You can find
all the words
(with Hungarian translations). I have found quite a few misprints and a few omissions,
so I wrote up
an errata (in English).

A list of the metres of all
poems in the book Faces of Love (a compilation of Persian poetry by three
Shirazi poets, translated by Dick Davis).
The metres are given also using Elwell-Sutton's numbering system.

A fusion of two earlier patches (MP and
GC), the Midpoint Coons patch boasts
computational efficiency and interior control. Read all about it in our
paper for the WAIT'17 conference.
Also there is a nice set of slides
(with a Star Trek reference).

I have worked trough all exercises in the 4th edition of "An Introduction to Persian"
(by W. M. Thackston), which was a very nice experience. You can find
all the words in the vocabulary lists
(with Hungarian translations). I have bought the key for this textbook,
but found that it had quite a lot of misprints and a few omissions, so I wrote up
an errata containing all errors and typos
I have found.

My first rejected paper!
It was a short submission to the Pacific Graphics 2016 conference.
While it does not have much theoretical contribution,
I think it still does a good job as a technical report,
so it deserves its place here.

The paper was polished a bit and
re-submitted to a small local
conference at our university (WAIT 2018). Thus the original version is removed.

Another new paper, this time for the bi-annual Hungarian
conference, contrasting multi-sided representations with fullness control,
and also introducing a very nice transfinite formulation, which we call the midpoint patch.

I have worked trough all exercises of "An Introduction to Koranic and Classical Arabic"
(by W. M. Thackston), which was a very nice experience. These are
all the words in the vocabulary lists
(with Hungarian translations). I have bought the key for this textbook,
but found that it had quite a lot of errors, even though most exercises used
sentences or passages from the Koran or from hadith literature, so I wrote up
an errata containing all errors and typos
I have found.

As an exercise, I've tried to write up a 20-page introduction to
Indonesian grammar (in Hungarian), covering (almost) all the basic
constructions, along with a worked out example text. The goal was to
create a document that can be read and understood with no previous
knowledge of the language.

A comparison between the generalized Coons patch and our version of
the Gregory patch was presented at the 10th Conference of the
Hungarian Association for Image Processing and Pattern Recognition.
This paper was accepted as a
poster
(PDF, Scribus)
displayed on a fullHD display.

All the words I have learned
from "Teach Yourself Beginner's Hindi" (R. Snell), "Teach Yourself Hindi" (R. Snell),
and "Living Language Hindi" (M. Bhat) - the latter lists containing only the words
not appearing in the previous ones.
There are also some grammar notes.
About using the dictionary file, see the
snippet page.

A new paper on creating G2 Gregory
patches over a curve network. It was presented at the Pacific Graphic
2014 Conference in Seoul, and it is published in the
Computer Graphics Forum
journal. A (less polished)
previous version was presented at the
Seventh Hungarian Conference on Computer Graphics and Geometry, 2014.

All the words I have learned
from "Teach Yourself Modern Persian" - both the wonderful 1971 version by John Mace,
and the awful 2004 version by N. Farzad, the latter list containing only the words not
appearing in the first.
There are also some grammar notes.
About using the dictionary file, see the
snippet page.

It was only much later when I realized that Korean is very easy to learn through Japanese.
So I bought 文法をしっかり学ぶ韓国語 and 前田式韓国語中級文法トレーニング,
and started it all over again (wordlist,
grammar notes).
About using the dictionary file, see the
snippet page.

A Greek (which is a
port of the modified
Emacs greek-babel input method),
a Latin (that contains
diacritical marks),
a Russian (which is a
port of the Emacs transliterated cyrillic input method),
a Turkish (which is a
prefix translation
of the Emacs turkish-postfix input method - another Emacs input method mimics
the (non-modified) characters of the Turkish Q layout),
a Persian (which is a
translation of the Emacs farsi-isiri-9147 input method),
an Arabic, implementing the
standard layout
(image from Wikipaedia),
and two Hungarian tables
for the Smart Common Input Method (SCIM). Place these files in
~/.scim/user-tables, and don't forget to edit the icon path in
the txt files.
There is also an Emacs port of
the SCIM JyutPing (Cantonese Big5) input method, and
a postfix Yoruba input method for
Emacs (not yet translated to SCIM).

My PhD dissertation on "Fair Curves and Surfaces",
along with its synopsis (in English and in
Hungarian), and
the theses booklet (in English and in
Hungarian).
The main results are also illustrated in the (Hungarian)
slides that I presented at the defense of
my dissertation.

As an exercise, I've tried to write up a 20-page introduction to
Swahili grammar (in Hungarian), covering (almost) all the basic
constructions, along with a worked out example text. The goal was to
create a document that can be read and understood with no previous
knowledge of the language.

Download the PDF
(there is also a cheat sheet),
or get the latest LyX source with
Git:

A description on configuring
my cheap Kraun gamepad to work under Linux. It involves downloading
various tools, hacking a kernel module and patching the SDL library -
all in a day's work for a programmer!

All the words I have learned
from "Colloquial Swahili" (D. McGrath & L. Marten) and
those I have learned
from "Teach Yourself Swahili" (J. Russell) and
those from
"Living Language Swahili" (Kh. Mohamed & A. Mazrui), containing only the
words not appearing in the previous lists.
There are also some grammar notes.
About using the dictionary file, see the
snippet page.

All the words I have learned
from "Colloquial Cantonese" (Keith S.T. Tong & Gregory James), along
with Hungarian meanings and chinese characters (also in
HTML version). There is
another list in text or
in HTML for
"Teach Yourself Cantonese" (H. Baker & P. Ho), containing only the
words not appearing in the first list.
About using the dictionary files, see the
snippet page.

All the words I have learned and some
grammar notes
(HTML)
I took (in Hungarian)
while learning from "Teach Yourself Arabic" (J. R. Smart) and other
sources, such as "Arabic - An Essential Grammar" (Faruk Abu-Chacra)
and "A New Arabic Grammar of the Written Language" (J. A. Haywood &
H. M. Nahmad). The words file also has a pattern search feature
(written in Emacs Lisp).

Another ASCII-based dictionary
contains all the words from the book "Teach Yourself Gulf Arabic"
(J. Smart & F. Altorfer).

There is also yet another dictionary
based on the words from the series العربية بين يديك
(Arabic Between Your Hands). About using the dictionary file, see the
snippet page.

Counting may be the most complex part of the Arabic language.
Here is a short (Hungarian) memo
with a few examples (also in HTML).

All the words I have learned and some
grammar notes
(HTML)
I took (in Hungarian)
while learning from "Introduction to Attic Greek" (D. J. Mastronarde).
This table contains sample words for
practicing every declension and conjugation I (should) know (there is
a filled version here, and
also in PDF format).
There is also a list of my solutions
to the exercises of the book "Homeric Greek - A Book for Beginners" (C. Pharr).
About using the dictionary file, see the
snippet page.

All the words
(html) I have learned and some
grammar notes
(html) (in Hungarian).
There is also a list of my solutions
(html)
to the exercises of the book "Latin for Beginners" (B. L. D'Ooge).
About using the dictionary file, see the
snippet page.

Some slides (in Hungarian) about CLOS and the conditions system
in Common Lisp, written for a class at university. Largely based
on Peter Seibel's talk at Google TechTalks, also his wonderful book
"Practical Common Lisp" and some other sources.

Available in OpenOffice
and PDF file formats.
There is also an archive
of the examples I have shown during the presentation.